From the U.S. Pat. No. 5,821,539 A1 a radiation detector is known comprising a direct conversion material in which incident high-energy rays are converted into movable electrical charges (electrons and holes). In order to remove charges that have been trapped in the converter material, an “injection electrode” is provided additionally to a conventional cathode and anode. It is mentioned that the metals of the electrode materials may diffuse into the adjacent converter material, thus generating a negative doping therein.